1. Field of the Invention
This invention relates generally to the attachment of internal equipment to pressure vessels. More specifically, this invention relates to pressure vessels containing high temperature particulate material and the attachment of high temperature internal partitions or baffles to relatively cold pressure vessel walls.
2. Description of the Prior Art
Common methods of processing chemicals and hydrocarbons routinely contact such materials with particulate materials comprising catalyst or adsorbents. High temperatures are frequently encountered in such processing so that containment vessels in which the particulate material and fluids undergoing processing or treatment are contacted often utilizing internal insulating lining on the inside of the metal containment vessel. The metal lining supports the insulating material and the insulating material lowers the temperature of the metal lining thereby permitting fabrication of the pressure vessel from less expensive metals.
Processing steps conducted within such vessels often require internal partitions to divide the internal area of the vessel into separate zones for carrying out processing steps or supporting internal equipment. The partitions often have a continuous circumferential attachment to the pressure containing vessel to seal different sections of the vessel from fluid or particulate flow. The continuous attachment of a partition that extends into the high temperature region of the containment vessel creates differential expansion between the relatively cold containment vessel shell and the much hotter partition attached thereto. This differential expansion deteriorates the structural integrity of the partition as well as any adjacent refractory lining.
One common form of such partition is in a regeneration vessel for the fluidized catalytic cracking (FCC) of hydrocarbons. In this process, the interior of the regeneration vessel operates at temperatures in excess of 1300.degree. F. A rigid concrete-like lining, referred to as a refractory lining, covers the inside of the regeneration vessel to insulate the containment vessel from the high internal temperatures. Many of the regeneration vessels are divided by an internal structure into an upper regenerator and a lower regenerator section. The internal structure normally has a frusto conical or cylindrical form with the lowermost point rigidly attached, in most cases welded, about a circumferential section of the regenerator shell. The higher temperature of the internal cone with respect to the colder regeneration vessel sometimes results in bulging of the vessel wall section, spalling or breakage of the refractory lining, and most often localized deformation of the internal structure, all at the point of attachment to the pressure vessel wall. The prior art has tried a number of arrangements to alleviate the deformation of pressure vessels and attachments at their junction; in particular, soft insulating linings, and air spaces to solve the aforementioned problems. Soft insulation with or without a flexible containment liner has replaced the rigid refractory lining at the localized section of a junction between a cold external shell and an internal partition. In addition, other arrangements interpose a flexible element at the junction of the cold vessel shell to the internal structure to permit expansion of the partition without imposing deforming stresses on the shell of the pressure vessel. The air space at the junction often loses its effectiveness due to the migration of particulate material, lining, or other debris into the air space.